The New Year losses follow a terrible year for US stocks. 2018 was the worst annual performance for stocks since 2008, and only the second year the Dow and S&P 500 fell in the past decade.

December was a particularly dreadful month: The S&P 500 was down 9% and the Dow was down 8.7% — the worst December since 1931. In one seven-day stretch, the Dow fell by 350 points or more six times.

2. China angst: Investor worries over China increased Wednesday after a survey of purchasing managers revealed new signs of weakness in the world's second biggest economy.

The manufacturing index, which is produced by media group Caixin and research firm Markit, fell to 49.7 in December from 50.2 in November.

It is this second time this week that data has indicated China's huge manufacturing sector is contracting.

"An increasing amount of data is pointing to the Chinese economy losing steam," said Jasper Lawler, head of research at London Capital Group. "With new orders falling for the first time in two and half years, the outlook doesn't look great either."

3. Chaos in Washington: An extended government shutdown in the United States is adding to investor fears.

President Donald Trump has invited congressional leaders from both parties to the White House, congressional sources told CNN. While details on the meeting are still being worked out, it likely will occur Wednesday.

The meeting would come as negotiations to re-open about a quarter of the federal government have been frozen for nearly two weeks, and just one day before Democrats take over as the majority party in the House.

While the government shutdown probably won't mean much for the economy in the near term, the impasse may portend bad news for a looming debt ceiling showdown.

Lawmakers must pass a law this year so the Treasury Department can continue to borrow without any restrictions. If they fail, the US government could default on its debt.

When that nearly happened in 2011, credit ratings agency Standard and Poor's downgraded America one notch below a perfect AAA. Another downgrade could make the country's massive debt load much costlier to pay back.